The present invention relates to a blood pressure measuring instrument, e.g. a sphygmomanometer and, more particularly, to a compensation circuit for such a blood pressure measuring instrument for detecting the Korotkoff sound without suffering variations in the piezo-electric properties.
In a conventional sphygmomanometer, there was provided a pressure sensor for determining the blood pressure and developing an oscillation frequency corresponding to the same. Piezo-electric elements of the pressure sensor was utilized for converting an amount of the blood pressure into the oscillation frequency. However, the piezo-electric elements inevitably suffer variations and nonlinear properties. This necessarily requires accurate examination and modifications in the pressure sensor.